1. Field of the Invention
The present invention relates generally to a method and apparatus for generating dithered image data for display of stereoscopic or 3-Dimensional (3D) images, and more particularly, to a method and apparatus for generating dithered image data that displays stereoscopic images to users of liquid crystal shutter glasses.
2. Description of the Related Art
As is well known, stereoscopic or 3D images may be made by displaying a pair of stereoscopic images, i.e., a left-eye image and a right-eye image, on display screens of 2-Dimensional (2D) media, such as Liquid Crystal Display (LCD) devices. If a viewer watches the right-eye images with the right eye and the left-eye images with the left eye, the viewer may recognize 3D images from the two stereoscopic images on the 2D media. Accordingly, the viewer may watch stereoscopic images when left-eye images and right-eye images are displayed on a 2D media in an alternating manner for the stereoscopic image display while wearing liquid crystal shutter glasses. The liquid crystal shutter glasses are designed such that the liquid crystals covering the left eye and the liquid crystals covering the right eye take turns enabling and disabling light transmission in an on/off manner synchronized with the predetermined period of the 2D display media.
In general, an LCD panel includes a lower substrate, an upper substrate with common electrodes, and liquid crystals sealed between the lower substrate and the upper substrate. The lower substrate has a plurality of thin film transistors TFTs arranged in a matrix consisting of rows and columns. Data lines are in the columns connected to the sources of the TFTs, gate lines are in the rows connected to the gates of the TFTs, and pixel electrodes are connected to the drains of the TFTs. Each pixel may include an associated pixel electrode, a common electrode, and liquid crystals between the electrodes. In order for the LCD panel to express colors, each pixel has primary-color sub-pixels, for example, Red (R), Green (G) and Blue (B) sub-pixels.
An LCD device is a device for driving an LCD panel to display images on the LCD panel. An LCD device typically includes a timing controller, a source or gate driver, and a data driver. The timing controller receives digital R, G and B data, control signals associated with operation modes, and a main clock from graphics controller cards of computers and/or broadcasting stations, and generates a first control signal including a gate or vertical start pulse GSP and a gate clock GCK, and a second control signal including a horizontal start pulse HSP, a horizontal clock HCK, and a data latch pulse DLP. The source or gate driver receives the first control signal and sequentially drives or scans the gate lines. The data driver receives the second control signal and the digital R, G and B data, and outputs, to the data lines, analog voltages indicating gray levels for the respective sub-pixels.
Dithering, which is a technique for changing the number of gray levels, is well known. The number of colors or gray levels expressible with the R, G and B data each having P bits is defined as 23P. However, if each of the R, G and B data is processed as data of an m×n dither sub-pixel block dithered using a dither pattern formed in an m×n dither sub-pixel block having m rows and n columns, the number of gray levels for each of the R, G and B data may increase m×n times compared with the number of gray levels expressible by each of the R, G and B data.
The above dithering technique has been used for display devices that are incorporated into devices such as cell phones and Personal Computers (PCs) to display images on the conventional 2D media. If this method of displaying dithered images on the 2D media is applied to the 3D image display method in which users watch images using liquid crystal shutter glasses, a dithering noise phenomenon such as flickering and horizontal-line patterns occurs on stereoscopic image screens. Thus, a new 3D image display method and apparatus is required that can prevent the dithering noise phenomenon.